Forgeable high speed steel



Patented Sept. 20, 1938 UNlTED STATES 2,130,822 FORGEABLE HIGH SPEED STEEL Elmer B.

Welch, McKeesport, Pa., assignor to Firth-Sterling Steel Company, McKeesport, Pa., a corporation of Pennsylvania No Drawing.

Application January 6, 1937,

Serial No. 119,263 1 Claim. (Cl. 75-126) This invention relates tohigh speed steels, and

more particularly to forgeable high speed steels containing a large total percentage of alloying elements. It is known that as the alloy content of high speed steels is increased, the difficulty in forging such steels also increases. Although my high speed steel contains high percentages of cobalt as well as lesser percentages of other alloying elements, it can be readily forged into the desired tool shapes. The alloy, in addition to cobalt, contains tungsten, chromium, vanadium, molybdenum and boron.

The high speed steel of the present invention 5 may contain 1 Table 1 Per cent Carbon .40- 1.0 Tungsten .50- 6.0 Chromium 3.0 7,5

Vanadium 5.0 Molybdenum 5.0 -12.0 Cobalt 20.0 -50.0 Boron--- .25- 2.0

25 The balance of the alloy is substantially iron.

A preferred range of the elements in my high speed steel is Table H Per cent 30 Carbon .50- .85

Tungsten 1.0 4.0 Chromium 4.0 6.0 Vanadium 2.0 3.5 Molybdenum 7.0 -10.0 35 Cobalt 25.0 45.0

Boron .50- 1.50

the balance of the alloy being substantially iron. A specific range of composition of my high the balance being substantially iron.

The high speed steel maybe made by melting the charge in the usual manner in an electric, induction or crucible furnace, it being preferred to add the boron as boron carbide. Since this carbide is light in weight, it is preferably placed at or near the bottom of the charge to prevent loss in melting. The boron can, however, be add- 0 edas ferro-boron, tungsten boride or other boron-containing alloy, although boron carbide is preferred.

After the charge has been melted, it may be cast into ingots, annealed, forged or rolled into suitable shape, and then heat treated. The in gots may be annealed I at a temperature of 1450 F.-1550 F. for about twenty-four hours, and the annealed steel forged into the desired shape at a temperature of about 1350 F.-1950 F.

In heat treating the steel, it may be heated to 2000 F.-2200 F., quenched in oil and drawn at 950 F.-1100 F. for one hour. It may be redrawn to impart additional hardness to it. For example, the steel heated to 2100 F., quenched in oil and drawn at 1025 F. for one hour had a Rockwell C hardness of 67. When this steel was reheated to 1050 F. for one hour, it had a Rockwell C hardness of 70.

The cutting properties of my alloy may be seen from a comparison of actual cutting tests, comparing it with a well known cobalt high speed steel which is now on the market.

The composition of my alloy was:

Per cent Carbon .64 Tungsten 1.41 Chromium 4.91 Vanadium 3.34 Molybdenum 8.15 Cobalt 32.30 Boron .89

the balance being substantially iron.

The cobalt high speed steel contained:

Per cent Carbon .75 Tungsten 18.50 Chromium 4.50 Vanadium 2.0 Molybdenum 1.0 Cobalt 9.0 Iron -2 Balance The cutting conditions were:

Cutting speed, 110 ft. per minute Depth of cut, in.

Feed, in.

The test log had a Brinell hardness of 225 and contained:

Per cent Carbon-.. .61 Silicon .29 Manganese .66 Sulphur -1 .034 Phosphorus .036

In a series of tests on the two types of steel,

my steel cut for an average of 135 minutes, as compared with an average of about,31 minutes for the other steel, the composition of which has been given. In other words, my steel cut for more than four times longer than the other steel now on the market.

I have described the preferred composition of my high speed steel and have described the manner in which it may be made and heat treated. It is to be understood, however, that the invention is not limited to the specific examples given, but may be otherwise embodied or practiced within the scope of the following claim.

Boron the balance being iron.

. ELMER B. WELCI-I. 

